Oil pump for an engine



v Filed Oct. 24. 1966 Sheet APril 1, 1959 KuNlb ATSUMI 3,435,914

OIL PUMP FOR AN ENGINE A ril 1, 1969 on. PUMP'F'OR AN'ENGINE Filed Oct.24, 1966 Sheet 2 of 2 KUNIO ATSUMI 3,435,914 7 3,435,914 OIL PUMP FOR ANENGINE Kunio Atsumi, Hamamatsu, Japan, assignor t0 Suzuki .Iidosha KogyoKabushiki Kaisha (trade name: Suzuki Motor Co., Ltd.), Hamana-gun,Shizuoka Prefecture, Japan, a corporation of Japan Filed Oct. 24, 1966,Ser. No. 589,015 Claims priority, application Japan, Oct. 28, 1965, 40/87,665 Int. Cl. F01m 1/02; F16n 7/36; F04d 15/00 US. Cl. 184-6 4 ClaimsABSTRACT OF THE DISCLOSURE Oil pump in which the oil distributor isdriven by a pump shaft interlocked with the engine and said pump shaftdrives sumultaneously a camshaft synchronized therewith. The cam carriedby said camshaft is in contact with a plunger which extends into thecylinder chamber of said oil distributor. The oil is supplied by slidingsaid plunger and successively connecting the oil hole communicating withsaid cylinder chamber to the suction and discharge holes surrounding thedistributor through rotation of said distributor. The profile of the camchanges in the axial direction in dependence on the relation between thecontact position of said cam and said plunger and the opening of theengine thorttle.

The present invention relates to an improvement in an oil pump forsupplying lubricating oil to those parts of an engine such as thecrankshaft, the connecting rod, the cylinder, the piston, etc., whichare subject to frictional wear, or more specifically to an oil pump forautomatically adjusting the supply of lubricating oil to such parts.

In this type of oil pumps it is generally desirable that the amount ofoil pumped increase with an increase in the r.p.=m. of the engine, so asto be proportional to the latter, and also that it increase with anincrease in the engine load. Moreover, such pumps are required to becapable of providing an uninterrupted supply of oil in an accurateamount to a working engine and to be so compact as to be suitable evenfor small engines such as those used for motorcycles.

In order to meet these requirements, the present invention provides anoil pump which is equipped with an oil :distributor interlocked with theengine, the quantity of oil supplied from said distributor beingdependent upon the degree of opening of the engine throttle.

In this invention, the oil distributor is driven by a pump shaftinterlocked with the engine and said pump shaft drives simultaneously acamshaft synchronized therewith. The cam carried by said camshaft is incontact with a plunger which extends into the cylinder chamber of saidoil distributor. The oil is supplied by sliding said plunger andsuccessively connecting the oil hole communicating with said cylinderchamber to the suction and discharge holes surrounding the distributorthrough rotation of said distributor. The profile of the cam changes inthe axial direction in dependence on the relation between the contactposition of said cam and said plunger and the opening of the enginethrottle.

Thus, in this invention, since both the pump distributor and thecamshaft are simultaneously driven -'by the engine, the oil supply ismade proportional to the r.p.m. of the engine and through properselection of the rotational position of the distributor and the camprofile, the plunger reciprocation can be exactly synchronized with theopening and closing of the suction and discharge holes. Moreover, sincethe cam profile changes in the axial direction nited States Patent OficePatented Apr. 1, 1969 of camshaft and the cam-plunger contact positionvaries in dependence on the throttle opening of the engine, the plungerstroke changes with the engine load, thus assuring the supply of oilwhich is necessary for lubrication.

In the present invention a plurality of discharge holes may be providedon the pump casing which encloses the oil distributor, and said oildistributor may be cylindrical. In this case it is possible for onereciprocation of the plunger to distribute the desired amount of oil toa plurality of parts by matching the cam profile to the angularpositions of the desired discharge holes. Moreover, a cylindrical formof distributor will not only be easier to manufacture, but will alsoassure very reliable valve action in the distributor, by providing veryaccurate connection and disconnection between the cylinder oil hole andthe successively opening suction and discharge holes.

In this invention the cam profile of the camshaft has the shape of atruncated cone, and it is proposed to pivot said camshaft to the pumpcasing so that it is axially movable and to interlock thus axial motionof said camshaft 'with the accelerator rod of the engine.

Thus, the cam profile will have a continuously smooth change of shape,assuring the desired stepless change; and this will give the advantageof precise synchronous motion directly interlocked with the working ofthe engine accelerator.

Also according to this invention, it is possible to provide anarrangement such that the axes of the oil distriIbutOr, pump shaft andcamshaft cross at right angles.

In consequence the whole pump can be designed very compactly without anyelongation of the plunger in the stroke direction. Only a small space istherefore for installation.

The other objects and features of this invention will be clearlyunderstood from the following description, with reference to theattached drawing, in which:

FIGURE 1 is a longitudinal section taken through an oil pump accordingto the present invention;

FIGURE 2 is a cross-sectional view taken along the line IIII of FIGURE1, in the direction indicated by the arrow;

FIGURE 3 is a cross-sectional view taken along the line III- III of FIG.1, in the direction indicated by the arrow;

FIGURE 4 is a developmental view showing the relation between theplunger stroke and the corresponding opening positions of the oilsuction and discharge holes;

FIGURE 5 is an elevational view showing the oil pump installed in atwo-cycle engine, with the side of its crankcase cut away; and

FIGURE 6 is a side view showing the oil pump as attached to an engine,illustrating the interrelation be tween said pump and the opening of thethrottle valve supplying the fuel.

Referring to FIGS. 1, 2 and 3, it will be seen that the oil pump Pcomprises a cylindrical distributor 3 which is an oil-tight fit into thetop longitudinal hole 2 in the pump casing 1.

The lower part of the distributor is formed into a worm gear 5 in anexposed position within the cavity 4 in said casing 1 and the plunger 7freely slides in a cylinder chamber 6, which is centrally positioned insaid distributor. A spring 9 extends between said plunger 7 and thecover 8 which closes the top longitudinal hole 2 in the casing 1. Thisspring normally biasses said plunger downward. The distributor 3 has anoil hole 10 communicating with the chamber 6 and extending radiallyoutward on one side. This oil hole 10 is in the same radial plane as thesuction hole 11 on one side of said pump casing 1 and a plurality ofdischarge holes 12, 12 spaced at predetermined angles on the other sideof the casing.

(Two such discharge holes are shown in the example illustrated in FIG.2.) Consequently the oil hole may come into communication with saidsuction hole and discharge holes successively as the distributor 3rotates in a manner hereinafter described. As seen from FIG. 5, thesuction hole 11 communicates through the duct M with the oil tank T,while the discharge holes 12, 12' respectively communicate through theducts N N with the friction producing parts of engine E such as thecrank shaft, connecting rod, piston and cylinder.

In the lower part of the pump casing 1, as shown in FIGS. 3 and 5 thepump shaft S connected to the crank shaft C of the engine E fits intothe lower cavity 4 above the bottom plate 13, said pump shaft beingrotatably mounted in the bearing 14 at the end of pump casing 1. On thepump shaft is formed a worm 15 which meshes with the worm gear 5 at thebottom of the distributor 3 and drives said gear. Below the pump shaftS, is a camshaft 16, which extends perpendicularly to pump shaft andruns beneath said distributor. The camshaft 16 is rotatably mounted inboth sides of the casing 1 by means of the bearings 17, 18. Saidcamshaft 16 carries a worm gear 19, which meshes with the worm 15 andhas the same number of teeth as the worm gear 5 and a cam 20 whichengages the plunger 7 which extends from the bottom of said distributor3 under the pressure of the spring 9. There is a recess 21 in the rightend of the camshaft 16 and a spring 22 positioned between the bearing 18and the end wall of this recess normally urges the camshaft 16 towardthe bearing 17 at the opposite side. The cam 20, as shown in FIG. 1, hasthe shape of a truncated cone when viewed in an axial plane, and isnormally in contact with the lower end of the plunger 7. But the cam 20,as seen from the developmental view shown in FIG. 4 (in which the solidline indicates the end of this truncated cone having the smallestdiameter, while the dotted line indicates the end having the largestdiameter), has a peripherally stepped cam surface. Beyond the bearing 17which receives the camshaft 16 is a control member 23 which is screwedinto said bearing 17 so that its tip is held against the end face ofcamshaft 16. At the outer end of the control member is a lever 24,which, as indicated in FIG. 6, is connected through a wire or a linkwith accelerator rod A to operate the throttle valve of the carburetterG. Therefore, when the rod A, shown in FIG. 6, is operated, the throttlevalve of the carburetter G will move at the same time as the lever 24.The action of the lever 24 will cause an axial movement of the controlmember 23 along the screw threaded groove within the bearing 17, thusmoving the camshaft 16 in an axial direction. Consequently, the plungerstroke, which depends on where the plunger strikes the truncated conecam 20, will change depending on the throttle opening of the carburetterG. Thus, with an increase in the r.p.m. of the engine E, the rotation ofcamshaft 16 will be accelerated, resulting in a faster reciprocatingmotion of the plunger 7. On the other hand, if the load on the engine Eincreases, or the throttle of carburetter G opens wider, the cam 20 willbe shifted, so that the plunger will contact a portion of the cam whichwill increase the stroke of the plunger. FIGURE 4 illustrates the aboverelationships, showing the shape of cam 20 the suction hole 11 and thedischarge holes 12, 12', the solid line showing the change of the strokea of the plunger 7 when the opening of the throttle -valve ofcarburetter G is narrow and the broken line showing the change of thestroke b of the plunger 7 when the opening of said valve is wide.

When the rotation of the crank shaft C is transmitted from the worm 15through the pump shaft S to the worm gears 5 and 19, which have the samenumber of teeth, and the distributor 3 and the camshaft 16 are therebysynchronously rotated, the plunger 7 is actuated by the cam surface ofthe cam 20 so that it reciprocates within the distributor 3, therebyeffecting the suction and discharging of the oil. As shown in FIG. 4,while the oil hole 10 of the distributor 3 is in communication with thesuction hole 11, the plunger 7 is in the suction stage and draws the oilfrom the oil tank T into the cylinder chamber 6. While the oil hole 10is in communication with the discharge holes 12, 12', the plunger 7 isin the discharge stage and supplies oil from the cylinder chamber 6through the ducts N N to each part of engine E which is subject tofrictional wear. If thereby the discharge hole 12 is brought intocommunication with the crankshaft at the same time that the dischargehole 12 is brought into communication with the engine cylinder, a singlereciprocation of the plunger 7 will suffice to distribute the oil to aplurality of parts. As the worm 15 assures synchronized rotation of thedistributor 3 and the cam shaft 16, the timing of the suction anddischarge of the oil can be accurately predetermined by proper selectionof the rotational position of the distributor 3 and the stepped shape ofthe cam.

From the above detailed description, it will be readily understood howthe present invention attains its intended objectives. The foregoingdescription, however, merely illustrates one possible embodiment of thisinvention and it goes without saying that various modifications andchanges can be made without deviating from the basic principles of theinvention as defined by the following claims.

What is claimed is:

1. An oil pump for an engine, said oil pump comprising a casing, a pumpshaft in said casing adapted to be driven by the engine, a rotatable oildistributor in said casing provided with a cylindrical chamber, acamshaft, both said distributor and said camshaft connected to berotated synchronously with said pump shaft, a cam carried by said camshaft, a plunger reciprocally mounted within the cylindrical chamber ofsaid distributor and having an end biassed into contact with said cam,an oil hole in said distributor communicating with said distributorchamber, an oil supply hole in said casing, and at least one lubricatinghole for communication with parts of said engine requiring lubrication,said supply and lubricating holes being positioned to be broughtindirvidually into and out of communication with said oil hole in saiddistributor in dependence upon the angular position of said distributor,the radius of said cam varying both axially and circumferentially, andmeans for varying the axial position of said cam in dependence on thethrottle opening of said engine, thereby to vary the stroke of saidplunger in said chamber.

2. An oil pump as claimed in claim 1, comprising a plurality oflubricating holes, and in which the oil hole in said distributor isrotated successively into communication with the single supply hole andsaid plurality of lubricating holes.

3. An oil pump as claimed in claim 1, in which the cam surface of saidcamshaft is in the form of a truncated cone, said camshaft being mountedfor axial movement in the pump casing, and said engine comprising anaccelerator pedal operatively connected to said camshaft to produceaxial movement of said cam shaft in response to movement of said.accelerator pedal.

4. An oil pump for engines as claimed in claim 1, in which thelongitudinal axes of said oil distributor, pump shaft and camshaft crosseach other at right angles.

References Cited UNITED STATES PATENTS 1,553,225 9/1925 Fekete et al18427 3,106,168 10/1963 Kolbe 10338 X 3,151,778 10/1964 Olney et a1.l03-38 3,298,238 1/1967 Lea 10338 X 3,302,752 2/1967 Shiokawa 1846 XHOUSTON S. BELL, 111., Primary Examiner.

U.S. Cl. X.R.

